PAPR-Aware Artificial Noise for Secure Massive MIMO Downlink

Abstract

This paper introduces a new approach to providing secure physical-layer massive multipleinput multiple-output (MIMO) based communications that can improve the energy efficiency of the system. This is achieved by synthesizing orthogonal artificial noise (AN) that has to be constrained to lie in the null space of the legitimate users' channels while it should lie in the range space of the eavesdropper's channel. In addition, this AN reduces the peak-to-average power ratio (PAPR) of the transmit signal. Indeed, low PAPR signals are preferable and more efficient for low-cost hardware, thus improving the energy consumption of massive MIMO systems. In this paper, we propose a new PAPR-aware precoding scheme based on the use of AN to enhance the secrecy performance of massive MIMO while reducing the PAPR of the transmit signal and guaranteeing excellent transmission quality for legitimate users. The scheme is formulated as a convex optimization problem that can be resolved via steepest gradient descent (GD). Accordingly, we developed a new iterative algorithm, referred to as PAPR-Aware-Secure-mMIMO, that makes use of instantaneous information to solve the optimization problem. Simulation results show the efficiency of our proposed algorithm in terms of PAPR reduction and secrecy, which is also studied with respect to power distribution between useful signal and AN, PAPR targets and the number of BS antennas.INDEX TERMS Artificial noise (AN), massive multiple-input multiple-output (MIMO), peak-to-average power ratio (PAPR), physical layer security (PLS), power allocation, steepest gradient descent (GD), zeroforcing (ZF) precoding.

Evaluation of the security performance of artificial noise‐aided STBC systems

“…The SC, $$C_{\text s}$$ is defined as the difference between the capacities at Bob and Eve, respectively, $$C_{\text b}$$ and $$C_{\text e}$$, as follows [4–8]: $$$$\begin{equation} C_{\text s} = \text{max}\lbrace 0,C_{\text b} - C_{\text e}\rbrace \end{equation}$$$$where $$$$\begin{eqnarray} {{C}_{\mathrm{b}}} & =& {\log}_{2}\left(1+\frac{||\mathbf{Z}\mathbf{h}|{|}^{2}/{N}_{T}}{{\sigma}_{\mathrm{b}}^{2}}\right),\nonumber\\ {{C}_{\mathrm{e}}}& =& {\log}_{2}\left(1+\frac{||\mathbf{Z}\mathbf{g}|{|}^{2}/{N}_{T}}{||\mathbf{W}\mathbf{g}|{|}^{2}/{N}_{T}+{\sigma}_{\mathrm{e}}^{2}}\right)={\log}_{2}\le...$$…”

“…The major contribution and novelty of this paper compared to the previous studies can be summarized as follows: Compared to the previous secrecy capability measurements for MIMO, for example, SC [4–8] and SOP [10–12, 16], the proposed method can provide the exact amount of information leakage to illegal listener. Compared to the previous study on the secrecy rate performance that is only applicable to SM [13–15], the proposed method presents secrecy rate formula that can be applied to any kind of STBC systems including AN‐aided STBC schemes. Compared to the previous study on the secrecy rate performance [13–15], the proposed method presents an approximated formula which can greatly reduce computational complexity. Compared to the previous study on AN‐aided STBC schemes [8, 9], this study provides extensive investigation on secrecy capabilities for various system environments, showing a trade‐off analysis between the security performance and power efficiency. …”

“…Massive machine type communications or internet of things (IoT) over wireless systems have attracted attention on security problems and encouraged the advent of physical layer security (PLS) technologies [1][2][3]. Over the years, a lot of efforts have been made for secrecy enhancements of MIMO systems [4][5][6][7][8][9][10][11][12][13][14][15][16]. Since the concept of the perfect secrecy has been established for a wiretap MIMO channel [4], artificial noise (AN)-aided PLS schemes have been considered as an effective means to improve communication security and various secrecy performance analyses have been reported [5][6][7][8][9][10][11][12][13][14][15].…”

“…Over the years, a lot of efforts have been made for secrecy enhancements of MIMO systems [4][5][6][7][8][9][10][11][12][13][14][15][16]. Since the concept of the perfect secrecy has been established for a wiretap MIMO channel [4], artificial noise (AN)-aided PLS schemes have been considered as an effective means to improve communication security and various secrecy performance analyses have been reported [5][6][7][8][9][10][11][12][13][14][15]. The role of AN is to add a noise that may cause serious interference with the illegal receiver, while causing no interference with the legitimate receiver.…”

“…As a measure of security performance of PLS schemes, the secrecy capacity (SC) concept was introduced and has been used in various studies [4][5][6][7][8]. For example, studies on AN-aided massive MIMO system formulated optimization problems by maximizing SC [5,6].…”